BACKGROUND: To compare data obtained through actigraphy with data from parental diaries to evaluate their concordance.METHODS: We enrolled 55 hospitalized infants aged 1-12 months with a gestational age higher than 35 weeks and without sleep disorders, complications due to perinatal events or movement deficits. They were monitored using both methods for 24 hours. Total diurnal and nocturnal sleep times and the numbers of awakenings were evaluated. Actigraph data were analyzed with Sadeh’s algorithm.RESULTS: Sleep time was analyzed in 51 infants. The average sleep time was 724.33 (±104.69) minutes according to the diaries and 625.18 (±109.14) minutes according to the actigraphy data, yielding a difference of 99.16 (±97.53) minutes (p<0.0001). The average number of awakenings was 8.65 (±3.78) according to the diaries and 13.43 (±5.09) according to the actigraphy data, with a difference of -4.78 (±4.50) (p<0.0001). A low concordance (≤0.66) was found between the two methods. The two methods provided different results (p<0.05) regarding nocturnal and diurnal sleep. After accounting for differences in disease and feeding types, the actigraphy and diary data were significantly different except for the number of daily awakenings. Concordances were higher in infants with respiratory diseases and those who were breastfed, except for the evaluation of nocturnal sleep.CONCLUSIONS: Concordance between actigraphy and parental reporting is low. Actigraphy may be a useful and easy to use method for collecting data on infants’ sleep than a parental diary, but actigraphy data should be analyzed in conjunction with infants’ passive movement records.